Metastatic thermometer



E. .N. HURLBURT.

METASTATIC THERMOMETER.

APPLICATION FILED sIzPT. 2|, 191s.

1,350, 158, Patented Aug. 17, 1920.

hummm UNITED STATES PATENT OFFICE.

yEDVVARI) N. HURLBURT, OF-ROCHESTER, NEW YORK, ASSIGNOR TO TAYLORINSTRU- MENT COMPANIES, 0F ROCHESTER, NEW YORK, A CORPORATION OF NEWYORK.

METASTATIC THERMOMETER.

Specification of Letters Patent.

Paten-ted Aug. 17, 1920.

Application filed September 21, 1916. Serial No. 121,384.

To all whom t may concern:

Be it known that I, EDWARD N. HURL- BURT, of Rochester, in the county ofMon roe and State of New York, have invented certain new and usefulImprovements in Metastatic Thermometers; and I do hereby declare thefollowing' to be a full, clear, and exact description of the same,reference being had to the accompanying drawings, forming a part or"this speciiication, and to the reference characters marked thereon.

My invention has for its purpose to prov vide a novel and improved formof metastatic thermometer by which is meant a differential thermometer',or one primarily adapted forl sensitively indicating slight changes froma given temperature rather than absolute temperatures expressed indegrees above a standard zero. Such a thermometer may4 be employed forvery accurate measurements of slight temperature changes, embodyinggenerally a graduated scale indicating small parts of a degree andcovering a range of six degrees'centigrade, for instance, and which canbe utilized to accurately indicate a very slight change of temperatureat any point of the centigrade scale. In a more specific aspect, theinvention resides in affording a structure that can be manufactured' ata reasonable cost, and in away that makes the device commerciallypractical from the standpoint of simplicity of operation, durability andresistance against breakage. To these and other ends the inventionconsists in certain improvements and combination of parts, all as willbe hereinafter more fully described, the novel features beingV pointedout in the claims at the end of the specication.

In the drawings: l

Figure 1 is a side view of a thermometer constructed in accordance witha preferred embodiment of my invention, and showing the heat expansiveliquidV column continuous throughout thetube; Y

Fig; 2 is'a similar view, illustrating-'the column of heat expansiveliquid after it is broken or separated at a designated 'portion ot' thetube, and with the surplus liquid, containedin the supplementalreservoir at one end of the tube;

Fig. 3 is an enlarged sectional view of thesupplemental reservoir at oneend of the tube;

Fig. l is an enlarged view in vertical section of the portion of thetube when the shape of the bore is changed, and

Fig. 5 is an enlarged View in horizontal section of the same.

Similar reference characters in the several iigures indicate the sameparts.

In its broad aspect, the invention comprises a tube having a bulb at oneend containing suitable heat expansive liquid; such as'mercury, and asupplemental reservoir at the opposite end for receiving the surplusliquid, that is to say, the amount over and above whatV is required inmaking each individual test or reading at any given temperature, aswillbe explained more fully presently. The principal part of the bore of thetube is roundedv in cross section as usual, but at one part fits sectionis so changed that while it has approximately the same carryingcapacity'or area the mercury column is rendered more rea'dilyfrangible.V

inclined with the bulb end uppermost, the! column of liquid'is broken orseparated by reason of the fact that the lm at the flattened portion isso attenuated that it is not sufficient to maintain a connection betweenthe adjacent'parts of the columru'w-hich is thereby separated,permitting the surplus liquid or that part on the opposite side of theseparation from the bulb to flow into the supplemental ,reservoir at theend of the tube. The portion of the liquid column between the bulb andthe flattened portion is then ready'to Vbe subjected to the temperatureof the body in which the test or reading is to be made. The supplementalreservoir for the surplus liquid is so constructed` and arrangedrelative'to the liquid column as to retain the latter, and prevent itfrom plusiage of the heatexpansive liquid'. The,

supplemental reservoir C is connected with ythe tube A by acomparatively long and gradually tapering passage D the sides of whichare convex in longitudinal section between the entrance of the bore andthe maximum diameter of the reservoir, as shown,

Vwhich serves to hold the surplus liquid withthe walls of the circularbore to yprovide a'V wide, thin passage through which the liquid canpass freely from one portion of the tube to the other. lVhile theopening at the portion E is of sufficient thickness to permit the fluidto pass readily from one part of the tube to the other, it is also ofsuch thinness as to spread the liquid into a very thin film, havinginsufficient strength to maintain itself when the tube is held in aposition generally horizontal or inclined to the vertical, with the bulbend uppermost. I prefer to use the term generally horizontal because,insome instances, due to unappreciable differences in the diameter of thebore, the column will break when the instrument is in horizontalposition, and in others a slight elevation of the bulb is required. Afinely graduated scale F is provided exteriorly of the tube and arrangedpreferably between the portion E and the reservoir C. The scale maybeofdifferent lengths and of different graduations, and in the constructionshown, embodies a range of siX degrees centigrade, divided intohundredths of a degree. The zero mark of the scale is located at a knowndistance from the constriction E, which, in the present instance is,preferably, the space corresponding to one degree on the scale, but ofcourse this distance may be varied to suit convenience, as will beapparent.

The operation of the thermometer briefly is as follows: The bulb isheated Vto cause the main body of liquidto rise in the tube until itmeets the surplus liquid in the supplemental reservoir, forming acontinuous liquid column. Assuming that a reading is to be taken of arise from twenty degrees centigrade, the bulb is placed in a bathmaintained at a temperature of nineteen degrees centigrade, or suchother temperature less than twenty degrees as is determined by the spacebetween' the zero of the scale and the constriction E, as determined bya seceond thermometer, and is held there until the fluid column comes torest. vThemetastatic thermometer is then removed from the bath and heldin a generally horizontal position, or inclined, with its bulb enduppermost, which causes the liquid column to break or separate at theportion E, and the liquid contained between this portion and thesupplemental reservoirimmediately flows into the latter and intherpresent construction is retained thereV through capillary action.

scale, so that a reading can be had for any rise within a range of-saysiX degrees above the startingpoint of twenty degrees centigrade.

The invention is not to be confined in any sense to the precisearrangement shown, and the application is intended to cover anymodifications embodying the underlying idea l of a tube having a bulb atone end and a supplemental liquid reservoir at the opposite end,combined with a portion so formed that,

while it will permit the main body of liquid to pass freely in eitherdirection, also permits it to be readily broken or separated to set thethermometer at any given temperature, this in the present embodimentbeing caused by varying the shape of the borewhile maintainingapproximately the same cross sectional area, as by flattening it. Theportion of the bore of the tube which is modified or changed may belocated either aboveor below the scale, and it may be made in other wayswithout departing from the intent or .scope of my invention. p

Thermometers such as shown herein, areV particularly adapted for use aselectrical contact indicating thermometers in which the metalliccontacts are fused in the glassinasmuch as they may be accurately set orregulated to vary the electrical indicating circuit at any giventemperature in a very fine degree and with a single thermometerdifferent temperatures may be indicated. I claim as my invention:

1. A metastatic thermometer comprisingV a tube containing heat expansiveliquid and having a portion of its rbore modified in form withoutmaterial variation of its cross x Vsectional area to permit the liquidto pass freely in either direction when held in a vertical position andto cause the liquid column to break or separate whenV the tube is placedin a generally horizontal position, a supplemental reservoir for surplusliquid at one end of the tube communicating with the bore, agraduated'scale for the tube, and a bulb at the opposite end of thelatter communicating with the bore.

2. A metastatic thermometer comprising a tube containing heat expansiveliquid and having a portion forming a wide thin opening adapted topermit free passage of 'thev liquid when held in a'vertical positionbuty adapted to spread the Vliquid into a thin film that readilyseparates or breaks when the tube is in a generally horizontal position,a supplemental reservoirrfor surplus liquid at one end of the tube, abulb at the opposite end of the tube, and a graduated scale on the tube.

3. A metastatic thermometer comprising a tube containing heat expansiveliquid and having a constricted portion forming a Wide thin openingadapted to permit free passage of the liquid When held in a verticalposition but adapted to attenuate the liquid into a thin lilm thatreadily separates or breaks When the tube is in a generally horizontalposition, a supplemental reservoir for surplus liquid at one end of thetube communicating with the bore, a graduated scale between theconstricted portion andthe reservoir, and a bulb at the opposite end ofthe tube communicating with the bore.

4. A metastatic thermometer comprising a tubecontaining heat expansiveliquid and having a portion of its bore modiedin form Without materialvariation of its cross sectional area to permit the liquid to passfreely in either direction when held in a vertical position and to causethe liquid column to break or separate When the tube is placed in agenerally horizontal position, a Ysupplemental reservoir for surplusliquid at one end of the tube communicating with thebore by a passageadapted to frictionally restrict the flow of liquid from said reservoirexcept when united by expansion with the liquid in the bore, a graduatedscale for the tube, and a bulb at the opposite end of the lattercommunicating with the bore.

EDWARD N. HURLBURT.

